1. Field of the Invention
This invention relates to a method for soldering, particularly in a furnace, the end part of a metallic pipe of a relatively small outside diameter of not more than about 30 mm laid generally in an automobile or other machine or device as a conduit for the supply of oil or air with a counter member through the medium of metallic fitting or a metallic base of a varying shape adapted as a joint.
2. Description of the Prior Art
The method heretofore employed for solding two metallic objects in a furnace has comprised inserting the connecting end part of a pipe member (P') as kept in its initial diameter into the connecting tubular wall (12) part of a counter member (11) by forcing the connecting end part into contact with the inner peripheral surface of the tubular wall or by tack welding the connecting end part and the connecting tubular wall (12) part through the operation of "clearance fit" or plasma welding, for example, as illustrated in FIG. 3, applying a soldering material to the neighborhood of the outer end peripheral part of the connecting tubular wall (12) part, and effecting mutual soldering (W') by the fusion attained as by passage through a furnace.
In accordance with the conventional method for soldering in the furnace as described above, owing to the structure of the pipe member (P') side connecting end part as kept in its initial diameter, the soldering material is not allowed sufficiently to permeate to the innermost part of the joining length while the connecting end part is pressed fast against the inner peripheral surface of the connecting tubular wall (12) part or the relative positions of the tubular member and the counter member are deviated and the soldering is attained unevenly with respect to the joining length or angle where the gap allowed for the purpose of "clearance fit" is unduly large. In the case of the tack welding as by plasma welding, the work itself is troublesome and the pipe member is liable to undergo deterioration of texture due to overheating because it has a smaller wall thickness than the connecting tubular wall. In any case, the conventional method has the problem that the pipe member side sustains cracks or fractures owing to inaccurate soldering coupled with the occurrence of vibration during the course of pipe installation.